The treatment of ocular diseases in mammals, including humans and non-humans alike often requires that drugs or other agents be delivered to the eye in a therapeutic dose. Such diseases may occur in the choroid, the retina, the crystalline lens, and the optic nerve, as well as other ocular structures. One treatment methodology is to deliver an ocular agent to these structures via local drug administration, as opposed to systemic drug administration. This permits agents to be delivered directly to a site requiring evaluation and/or therapy. Because of drug localization, there is less of a concern for release or dissemination of the drug beyond the site of delivery. Such is also the case for other body sites where it is desirable to limit drug dissemination or systemic administration, yet still provide drugs in various formulations.
In many instances, however, local drug administration to the eye is not easily accomplished. Thus, localized drug administration often requires rather invasive procedures to gain access to the various ocular structures being treated. This may entail inserting a conduit, such as a fine gauge needle into the eye, or forming an incision for positioning of a device, such as a drug depot. Consequently, such treatment typically requires a visit to a hospital or doctor's office where trained health care professionals can perform the necessary, relatively more invasive procedures to achieve local drug administration.
Another form of localized drug delivery may be accomplished using iontophoresis. Although iontophoresis is generally well-accepted by patients and medical professionals, there are some risks involved. For example, high current intensity or long treatment times can lead to pain, burning sensations, skin irritation, erythema, blister formation, and skin necrosis. In the most extreme cases, high currents produced by direct current iontophoresis can short through a patient's heart. Iontophoresis also requires reformulated compounds for application and, thus, cannot typically use market-available drugs.